In the related art, there is widely used a three lens group zoom lens as zoom lenses of various cameras, which is capable of reducing size and excellently correcting aberrations.
Meanwhile, according to a digital camera or a video camera spreading rapidly in recent years, small-sized formation, high image quality and low distortion of lenses have been desired similarly to those used in general cameras.
Further, according to a digital camera or a video camera, automatic focusing is mainly adopted and high speed formation of focusing has been desired. Therefore, there is frequently used a focusing system of zoom lens of an inner focusing type or a rear focusing type capable of lightening a lens weight, placing lenses proximate to a camera main body side and facilitating driving operation. In such zoom lenses, from a view point of achieving small-sized formation, high image quality and low distortion of lenses, it is preferable to constitute lenses by three groups rather than constituting lenses by two groups.
There are known such three group zoom lenses adopting a rear focusing system, achieving high speed formation of focusing and small-sized formation (refer to, for example. JP-A-2003-140041), achieving wide field angle formation (refer to, for example, JP-A-2003-107348).
However, in recent years, there is also increased request for zoom lenses having wider field angle in addition to small-sized formation and high function formation of an optical system.
In this respect, according to the zoom lenses described in JP-A-2003-140041, a first lens group is constituted by two lenses in order to achieve small-sized formation and therefore, a field angle at a wide angle end becomes about 65 degrees, and wide angle formation is not achieved sufficiently.
Further, although according to zoom lenses described in JP-A-2003-107348, a field angle at a wide angle end is as wide as about 77 degrees, however, since a second lens group is constituted by five lenses, small-sized formation is not achieved sufficiently.